Marijuana legalization is expanding, but is it truly safe for the heart? Two recent studies add to the growing body of evidence suggesting that cannabis users face a significantly higher risk of heart attacks—even among younger, otherwise healthy adults. A retrospective study analyzing data from over 4.6 million individuals, published in JACC Advances, and a meta-analysis of 12 prior studies presented at the American College of Cardiology’s Annual Scientific Session (ACC.25), highlight these concerning trends.
As marijuana use rises in the United States, particularly in states where recreational use is legal, researchers have uncovered troubling statistics. In the retrospective study, individuals under 50 who used cannabis were over six times more likely to experience a heart attack than non-users. The meta-analysis, the most extensive pooled study to date on this topic, found a 50% increased risk of heart attack among cannabis users.
Healthcare providers should incorporate cannabis use assessments into routine cardiovascular risk evaluations, much like they do with cigarette smoking. Public health policies should also include clear warnings to inform users about potential cardiovascular risks.
“Understanding a patient’s cannabis use is crucial for assessing overall cardiovascular risk,” says Dr. Ibrahim Kamel, the study’s lead author and a clinical instructor at the Boston University Chobanian & Avedisian School of Medicine. “Patients need to be aware that cannabis consumption is not risk-free.”
Dr. Kamel and his team conducted the retrospective study using data from TriNetX, a global health research network that provides access to electronic medical records. Over an average follow-up of more than three years, cannabis users had more than a sixfold increase in heart attack risk, a fourfold increase in ischemic stroke risk, a twofold rise in heart failure risk, and a threefold higher likelihood of cardiovascular-related death, heart attack, or stroke. All study participants were under 50 and had no significant cardiovascular conditions at baseline. Their blood pressure and LDL cholesterol levels were within normal ranges, and they had no history of diabetes, tobacco use, or coronary artery disease.
For the meta-analysis, researchers compiled data from 12 studies involving over 75 million people. These studies, rated as having moderate to good methodological quality, included research from the United States, Canada, and India. While some did not specify participant ages, the average age among those that did was 41, indicating a relatively young sample.
Of the 12 studies, seven found a significant link between cannabis use and heart attacks, four showed no significant difference, and one suggested a slight negative association. However, when all data were pooled, cannabis users were found to be 1.5 times more likely to experience a heart attack than non-users.
Despite this evidence, the researchers acknowledged some limitations. Cannabis use and heart attack risk were assessed similarly across the studies, but inconsistencies in available data prevented them from fully accounting for confounding factors such as frequency and duration of cannabis use, or simultaneous use of tobacco and other substances. “Cannabis consumption is often linked with other drugs, which may contribute to these cardiovascular effects,” Dr. Kamel cautions. “Patients should be honest with their doctors about all substance use to get the best possible care.”
The exact mechanisms by which marijuana affects cardiovascular health remain unclear. However, researchers theorize that cannabis may disrupt heart rhythm regulation, increase oxygen demand in the heart muscle, and impair endothelial function, making it harder for blood vessels to relax and expand. One study in the meta-analysis reported that the risk of heart attack peaked about one hour after marijuana use.
Since both the retrospective study and the meta-analysis have inherent limitations, researchers emphasize the need for further prospective studies to confirm the findings and identify the highest-risk groups.
Previous research has already suggested a link between daily marijuana use and coronary artery disease. As cannabis becomes more widely available, continued investigation into its long-term cardiovascular effects will be crucial for public health.
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